(a) Field of the Invention
The present invention relates to a multi-channel optical module device.
(b) Description of the Related Art
Recently, a physical quantity measurement system such as an FBG (fiber Bragg grating) sensor interrogator that requires a wideband light source has been used. However, the wideband light source is expensive and its size is large, which presents many use limitations.
A light source for solving this problem has been developed. Specifically, light outputted from a plurality of laser diodes that have the same optical power and different center wavelengths is coupled by an optical coupler and then is outputted to an optical fiber. After that, current inputted to each laser diode is sequentially modulated (as a result, the output wavelength of the each laser diode is modulated by many nanometers) so that the wavelength of the light outputted from the final output channel varies by tens of nanometers. The light source of this type has been developed. For instance, if the center wavelengths of the laser diodes are λ1, λ2, λ3, . . . , λN (here, the optical intensity of the laser diodes has to be similar), respectively, when the center wavelength of each laser diode varies by a according to the current modulation (here, the a has to be larger than the difference between the center wavelengths of the laser diodes), the wavelength of the final output light obtained by coupling a plurality of laser diodes, that is, N light sources, may vary by αN.
However, optical loss in the optical coupler itself is very large, and in order to form an output channel having different tunable wavelength ranges, an optical coupler having the required number of channels has to be used in the beginning of manufacturing an optical module device.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.